How many field mice are born? - briefly
Field mice generally have 4–7 pups per litter and produce two to three litters each breeding season, resulting in about 10–21 offspring per female each year. This estimate varies with species, habitat quality, and seasonal conditions.
How many field mice are born? - in detail
Field mouse reproduction is rapid and prolific. Females reach sexual maturity at six to eight weeks and can produce multiple litters during the breeding season, which in temperate zones extends from spring through early autumn. A single litter typically contains four to seven offspring; average litter size is about five. Most females produce three to four litters annually, resulting in an estimated 12 to 28 young per female each year.
Key variables influencing birth numbers include:
- Season length – longer warm periods allow additional litters.
- Food abundance – high seed and insect availability raise litter size and survival rates.
- Population density – overcrowding suppresses breeding frequency through social stress.
- Predation pressure – intense predation reduces the number of surviving juveniles, indirectly affecting subsequent reproductive output.
- Habitat quality – dense ground cover and adequate nesting sites support higher reproductive success.
In optimal habitats, field mouse density can reach 30–50 individuals per hectare. With the average annual production of 15–20 offspring per female, a hectare may generate 450–1,000 newborns each breeding season, assuming a balanced sex ratio and minimal mortality. In less favorable conditions, these figures drop sharply, sometimes to fewer than 100 births per hectare.
Overall, the reproductive capacity of field mice enables swift population growth when environmental constraints are minimal, while adverse factors can markedly reduce the annual number of newborns.